Chelsea's first-half authority was eroded by David Luiz's own goal and a third at the death from the PSG substitute Javier Pastore but Mourinho again saved heavy criticism for his forwards.

The Portuguese omitted Fernando Torres from the starting lineup after an ineffective display in the defeat at Crystal Palace on Saturday, preferring the winger André Schürrle in a central role rather than either the club's £50m record signing or Demba Ba. Torres did emerge from the bench for the last 31 minutes but made minimal impact.

PSG's second-half goals owed much to the uncharacteristic generosity of Chelsea's defending, with Mourinho disgusted particularly by Pastore's strike after the Argentinian beat César Azpilicueta and Frank Lampard before converting inside Petr Cech's near post.

"We scored in our own goal, and the third goal … it's a joke," said the manager. "Not a goal, a joke. Gary Cahill said it was sloppy but I say it was ridiculous. It was Pastore and us.

"In the second half we made individual mistakes in areas where, for the whole season, the guys have performed with no problems. They have the right to make the mistakes because we have other players who have made some mistakes all season.

"From a strategic point of view, the team had great discipline and did the most difficult things to do in the game. They stopped [Zlatan] Ibrahimovic when he dropped back to play in the midfield and between the lines, and he was completely under control. Edinson Cavani was completely under control. The positional play from Marco Verratti and Thiago Motta was under control, as were their full-backs, but we couldn't transform our half-chances into goals. And on top of that we made defensive mistakes, individual defensive mistakes, so we paid the price.

"At the first goal the ball goes to [Ezequiel] Lavezzi and he controls the half-volley and 'boom'. Top player. Top striker. It's been difficult for us to score goals, especially when the games are tight. It's difficult for us to transform the half-chances into chances. And when you make the defensive mistakes, you are in trouble. That's, for me, simple. We are not a team full of talent to score goals – especially at this level but you never know."

Asked about his decision to start with Schürrle rather than Torres, the only striker at the club who has registered away from Stamford Bridge this season, in the absence of the hamstrung Samuel Eto'o, Mourinho explained: "I'm not happy with my strikers' performances, so I have to try things. And with André at least I know we have one more player to have the ball, one more player to associate with the other players, and even if he is not dangerous because he's not a striker, he can associate and the team can have control of the ball possession like we had.

"But football is not just about that. It's also about scoring goals, getting behind, and that is for strikers. Real strikers. And I had to try. We are not out, and we have nothing to lose now.

"We have to play thinking that it's possible. And, to be fair, I don't think Paris think it's over. I don't think they think it's done. They feel they are in a good position but I think they know that it's not over. It's a tough job, not impossible, but difficult."

PSG expect to be without Ibrahimovic for Tuesday's return at Stamford Bridge after the Swede limped away from the second half after damaging the hamstring in his right leg, with further scans to be undertaken on Thursday. The club's president, Nasser al-Khelaifi, told French TV the striker would be out of action for two to three weeks.

PSG's manager, Laurent Blanc, said: "This was a big performance for us. The third goal changes things a bit. We will see next week just how much."